<style>
    .balls{
        border-radius: 50%;
        position: fixed;
        width: 50px;
        height: 50px;
        margin-top: 50px;
        animation-name: bounce;
        animation-duration: 2s;
        animation-iteration-count: infinite;
    }
    #red {
        background: red;
        left: 27%;
        animation-timing-function: cubic-bezier(0, 0, 0.58, 1);
    }
    #blue {
        background: blue;
        left: 56%;
        animation-timing-function: ease-out;
    }
    @keyframes bounce {
        0% {
            top: 0px;
        }
        100% {
            top: 249px;
        }
    }
</style>
<div class="balls" id= "red"></div>
<div class="balls" id= "blue"></div>